Fresh Water Impairments

The fresh waters of the Narragansett Bay Region—rivers, streams, lakes, ponds and ground water—are a critical natural resource, providing habitat for fish and wildlife, drinking water for about two million people, and exceptional opportunities for recreational boating, fishing and swimming. The status of NBR’s fresh water resources is affected by development patterns within the watershed. During the past half century, suburbanization throughout NBR has significant redistribution of population. As people move from urban centers to rural areas, infrastructure follows and the accompanying roads, houses, schools and businesses affect water quality.
In the Narragansett Bay Region in recent decades, major investments in Waste Water Treatment Facilities (WWTFs) have resulted in marked water quality improvements. Overall, the water quality of the state’s major rivers are impacted by both point and non-point sources, whereas stormwater and nonpoint sources — rain runoff from developed landscapes — are the predominate sources to lakes.

These indicators are taken from state (R.I. and Mass.) biennial integrated assessments of water quality — the R.I. 2008 Integrated Water Quality Monitoring and Assessment Report, and Massachusetts Year 2008 Integrated List of Waters. These assessments bring together water quality data collected by a variety of organizations including state and university scientists and trained citizen volunteers. In Rhode Island, RIDEM monitors rivers and streams using a rotating basin approach that was adopted in 2004. The approach integrates biological, chemical and physical monitoring to characterize water quality conditions throughout a watershed. RIDEM will have completed monitoring of all targeted rivers and streams in the state using the rotating basin approach by the fall of 2009.

Bacteria:

Bacteria are used as an indicator of the safety of fresh waters for human contact such as swimming. The bacteria measured (fecal coliform or enterocci) originate in the intestines of warm-blooded animals: their presence indicates that fecal contamination may have occurred and pathogens may be present in the water. Sources of bacterial contamination of rivers, streams, lakes and ponds are similar to those for estuarine waters and include stormwater runoff from developed landscapes that may carry bacteria from pets, domestic animals, waterfowl and other wildlife, as well as human waste from failed or substandard septic systems and in some locations sewer system overflows (SSOs) or combined sewer overflows (CSOs).

* Not all waters are assessed for these parameters

Dissolved Oxygen:

Dissolved oxygen concentrations (DO) are an important indicator of ecosystem health. Oxygen concentrations are affected by physical and biological conditions. Oxygen is introduced to rivers and streams through the aerating action of wind or turbulence and from plant photosynthesis during daylight hours. Oxygen concentrations are consumed by the decomposition of organic matter and respiration by aquatic animals and plants. If more oxygen is consumed than is produced, DO concentrations decline and some sensitive animals may disappear. DO levels fluctuate daily and seasonally. They also vary with water temperature - cold water holds more oxygen than warm water. The most critical time for many aquatic animals is early morning on hot summer days, when river flows are low, water temperatures are high, and plants have not been producing oxygen since sunset.

* Not all waters are assessed for these parameters

Nutrients:

Aquatic plants and algae require nutrients (primarily nitrogen and phosphorus) to grow and survive. In fresh water as in estuarine areas, however, an over-abundance of nutrients can cause eutrophication—excessive plant growth which degrades habitat and interferes with human uses such as boating and swimming. In lakes, ponds and slow-flowing river segments, excessive plant growth can cause DO concentrations to fluctuate – becoming very high during the daylight hours when the plants are photosynthesizing, and very low (or absent) during the night hours. Point sources such as WWTFs, CSOs and storm drains contribute nutrients to rivers and streams, while non-point sources (primarily stormwater runoff from developed areas) carry nutrients from fertilizer, animal waste, septic systems and other sources.

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